Polyoma BK Virus in Kidney Transplant Recipients: Screening, Monitoring and Management.

Polyomavirus BK virus (BKPyV) infection is an important complication of kidney transplantation and allograft failure. The prevalence of viremia is 10-15%, compared with BK associated nephropathy (BKPyVAN) at 3-5%. Given that there are no effective anti-viral prophylaxis or treatment strategies for BKPyVAN, active screening to detect BKPyV viraemia is recommended, particularly during the early post-transplant period. Immunosuppression reduction to allow viral clearance may avoid progression to severe and irreversible allograft damage. The frequency and duration of screening are highly variable between transplant centers because the evidence is reliant largely on observational data. Whilst the primary treatment goals center on achieving viral clearance through immunosuppression reduction, prevention of subsequent acute rejection, premature graft loss and return to dialysis remain as major challenges. Treatment strategies for BKPyV infection should be individualised to the recipient's underlying immunological risk and severity of the allograft infection. Efficacy data for adjuvant therapies including intravenous immunoglobulin and cidofovir are sparse. Future well-powered and high-quality randomized controlled trials are needed to inform evidence-based clinical practice for the management of BKPy infection.